Five Fundamental Aspects of Client-Side Performance Testing

Performance Testing helps to assess the quality assurance of an application. It ensures that the application delivers stable and consistent performance under the expected load. The testers use tools and appropriate frameworks to gauge the errors, bugs, bottlenecks, and response time of the app. To develop the right strategy for performance testing, the QA team must identify the metrics for performance requirements. The requirements can be gathered by contacting different clients or using server log activity. These metrics help to monitor and analyze the app performance and identify ways to improve it.

Most of these apps are a mixture of server-side and client-side codes. Hence, besides optimizing the server-side rendering, it is critical for the developers to test how the app delivers its functionalities on the client-side. The client-side is the code that runs on the users’ hardware. Employing the client-side metrics in performance testing, the QA can test if the app performs well and provides a significant user experience through optimized front-end features. The QA put themselves in the place of the end-users to evaluate how the front-end rendering of the app, and assess its response time. If the app takes longer to load, it is subjected to higher chances of abandonment.

While server-side testing evaluates logical scenarios, such as server response time and app behavior under user load, client-side performance testing helps to evaluate end-to-end scenarios. Here are few important fundamental aspects of client-side performance testing.

Importance Of Client-Side Performance Testing

Client-side performance testing is used to test the rendering of front-end elements like CSS and JavaScript files. It helps to check the app from a user perspective hence the QA must perform and behave like end-users. Client-side performance tests are generally of three types. It is performed on a desktop browser, mobile devices, and with limited resources of CPU, memory, network, localization, and more. As a part of non-functional tests, it helps to check the app performance in a real-world scenario, and validate the app against used expectations. It allows you to address the gaps in front-end elements of the app, and identify risks related to client-side performance.

Common Client-Side Performance Pitfalls and Best Practices to Avoid It

The common issues in client-side performance are unused CSS, blocking resources rendering, images compression and format, and JavaScript (JS) execution time. To avoid this, you can use images and JS code in compressed form. JS code minification, JS code compression, unused JS code removing, and JS code caching to improve JS execution time. Enabling better cache techniques helps to provide faster response time to users. Removing unnecessary static page resources (CSS and JS) helps to effectively bring down rendering time. One of the most important testing practices is to conduct server-side performance before moving ahead with client-side testing. Server response time still matters, and if it can render fast but doesn’t get any response, it will affect your end-user experience.

Important KPIS of Client-Side Performance Testing

Some of the important metrics of client-side performance testing are:

  • TTFB (Time to First Byte): The time between the first byte of the user request and the first byte of the server response.
  • Payload: It refers to the web page content size
  • Speed Index: It refers to the average time it takes to display content on the web page
  • Load Time: It refers to the time taken to completely load the web page content
  • Time to Render: It refers to the time take to process and display web page elements to users
  • Time to Interact: It is the time taken to interact with the first web element
  • CPU Idle Time: The time for which CPU’s main thread remains idle and waits for any response from third-party requests.

Client-Side Performance Priorities

  • Basic text and layout: The visible page framework should load in minimal time and the important textual elements must be the incorrect location.
  • Functional elements: The visibility and responsiveness of the functional elements on the page are tested.
  • Formatting and images: The pages on which the graphics are secondary, CSS, and graphics can load after the functional elements.

Which Environment to Use for Client-Side Performance Testing?

For Client-side performance testing, the app must be present in an environment similar to production. The app must be ready for non-functional tests, and you need to run the tests in a real-world scenario. Execute tests on real content for client-side performance testing to get optimal results. Some of the basic metrics are Speed Index and Time to Interact. Speed Index refers to the average time the page requires to display its visible parts. Time to interact is used for determining the interactivity of the page by the network and JS activity. If real content is unavailable, you can prepare a production-like environment with new code to run these tests.

To Conclude:

Client-side performance testing is key to smooth CX. With the advanced tools, you can also automate these tests to assess the front-end rendering of the app. You can easily identify front-end performance bottlenecks, and optimize their performance to provide an enhanced user experience.

RJ Frometa
Author: RJ Frometa

Head Honcho, Editor in Chief and writer here on VENTS. I don't like walking on the beach, but I love playing the guitar and geeking out about music. I am also a movie maniac and 6 hours sleeper.

About RJ Frometa

Head Honcho, Editor in Chief and writer here on VENTS. I don't like walking on the beach, but I love playing the guitar and geeking out about music. I am also a movie maniac and 6 hours sleeper.

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